Employing root beer as the backbone of an entire multi-course meal evokes a sugary, syrupy childhood dream on a par with eating ice cream for breakfast — a sweet idea that probably can't end well.That is, unless you're talking to chef Paul Turano, whose team is preparing to host Tryst Restaurant's fourth annual Tower Root Beer dinner at the Arlington Center eatery on Sunday. There's nothing childish about sassafras-glazed quail, and a house-made all-beef hot dog served with root beer-braised baked beans is about as sophisticated as a hot dog can get; both dishes were hits at root beer dinners past.The collaborative event pairs a 100-year-old Somerville tradition with innovative dishes and cocktails.Turano said he was first turned on to Tower a few years ago, when the third generation of Cusolitos revived the family recipe and reintroduced Tower Root Beer to the market.The beverage company was created in 1914 by Domenick, Giuseppe and Felice Cusolito, and its ginger ale and root beer helped quench peoples' thirst during Prohibition, when beer and other alcoholic drinks were illegal and more difficult to find, according to the company. Its ginger ale was also used as a mixer to help cover the taste terrible-tasting whiskey being made during that time, according to the company.Tryst began carrying the beverage and the flavor profile caught Turano's attention.“It definitely has a distinct flavor,” said Turano. “It's not like the generic soda taste. There's a lot more spice to it.”Turano added that Tower packs in molasses, fennel and licorice flavors, creating “more of an adult root beer.”That first dinner, he said, was an experiment, a variation on the theme of popular beer and wine dinners.“By the time the dinner was over we were so proud of it,” he remembered. “It was a great challenge, it was out of the norm, and we wanted to keep going and try to top the year before.”Each dish served at the dinner will have a main root beer component, Turano said. The biggest challenge is trying to make sure nothing comes out too sweet. But Tower's unique, complex flavor lends itself to the process.Turano prides himself on having a restaurant that offers "unpretentious" but high quality food, in the 100-seat restaurant he opened on Massachusetts Avenue in 2004.Turano said he's seen many familiar faces at the root beer dinners. Although the concept is the same each year, the dishes are always new.“I think it's a surprise from start to finish,” he said. “We get the greatest feedback from this dinner. It's just very different from the day-to-day. I think between the cocktails and the food and the experience and meeting the [Cusolito] family … you can't top it. It's a 10.”Turano's team includes chef Dan DeCarpis and sous/pastry chef Michelle Jones.The dinner begins at 6 p.m. on Sunday, July 27, at Tryst Restaurant, 689 Mass. Ave. The prix fixe menu costs $34 per person, or opt for the meal with cocktail pairings for $48 per diner. Reservations are required; call 781-641-2227 or visit trystrestaurant.com.